Struct sway_core::query_engine::CowCache

pub struct CowCache<T: Clone> { /* private fields */ }

Thread-safe, copy-on-write cache optimized for LSP operations.

Addresses key LSP challenges:

1. Concurrent read access to shared data
2. Local modifications for cancellable operations (e.g., compilation)
3. Prevents incomplete results from affecting shared state
4. Maintains consistency via explicit commit step

Uses Arc<RwLock<T>> for shared state and RwLock<Option<T>> for local changes. Suitable for interactive sessions with frequent file changes.

Implementations

impl<T: Clone> CowCache<T>

pub fn new(value: T) -> Self

Creates a new CowCache with the given initial value.

The value is wrapped in an Arc<RwLock<T>> to allow shared access across threads.

pub fn read(&self) -> impl Deref<Target = T> + '_

Provides read access to the cached value.

If a local modification exists, it returns a reference to the local copy. Otherwise, it returns a reference to the shared state.

This method is optimized for concurrent read access in LSP operations.

pub fn write(&self) -> impl DerefMut<Target = T> + '_

Provides write access to a local copy of the cached value.

In LSP, this is used for operations like compilation tasks that may be cancelled. It allows modifications without affecting the shared state until explicitly committed.

pub fn commit(&self)

Commits local modifications to the shared state.

Called after successful completion of a compilation task. If a task is cancelled, not calling this method effectively discards local changes.

Trait Implementations

impl<T: Debug + Clone> Debug for CowCache<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Default + Clone> Default for CowCache<T>

fn default() -> CowCache<T>

Returns the “default value” for a type.